Localization of binding sites of naturally occurring antisperm antibodies on human spermatozoa by immunofluorescence

Immune infertility in men

Male factors are implicated as the cause of roughly half of cases of infertility, and the presence of antisperm antibodies (ASA) may be responsible for some of these. Their presence is associated with a reduction in natural conception and live birth and impacts the success of assisted reproductive technologies. Interpretation of the data regarding ASAs and fertility is complicated by a lack of standardization in testing methodology and test thresholds and a lack of data on their prevalence in the healthy fertile population. Although their pathogenesis remains elusive, and many cases are idiopathic, a disruption in the immunologic blood-testis barrier (BTB) appears to contribute to the formation of ASA. As delineation of the specific antigen targets of ASA advances, it has been recognized that they may affect almost all aspects of sperm function, and ASA against different targets likely have specific mechanisms of impairing fertility. Intracytoplasmic sperm injection (ICSI) appears to be the most reliable method by which to overcome fertility impairment due to ASA, achieving similar outcomes to ASA-negative patients with regard to fertilization rates, embryonic development, clinical pregnancy rates, and live birth rates. The lack of consistency in testing for and reporting ASA remains a substantial barrier to achieving clarity in describing their role in infertility and the optimal management approach, and future research should use a unified approach to the detection and description of ASA. Determination of the specific antigens targeted by ASA, and their function and clinical relevance, would contribute to improving the understanding of ASA-mediated impacts on fertility and tailoring treatment appropriately to achieve the best outcomes for patients.

Human MOSPD2: A bacterial Lmb mimicked auto-antigen is involved in immune infertility

Autoantibody production is one of the leading factors of immune infertility, an autoimmune disease of the male reproductive system. The potential involvement of MHC-class II derived self-peptides against bacterial proteins in the antisperm antibody (ASA) production has been reported previously. Apparently, Streptococcus agalactiae has been considered as an important pathogen to impart infection-induced infertility in a bacteriospermia associated leukocytospermia (LCS/BS) state. Hence, the present study attempts to confirm S. agalactiae specific Laminin binding protein (Lmb) derived self-peptide ('KDSYTKKAKAFKKEA') namely human Motile Sperm domain-containing protein 2 (MOSPD2) as an auto-antigen in LCS/BS condition. Semen samples were collected from infertile men with LCS/BS (n ​= ​17) and their fertile counterparts (n ​= ​10). Gram-positive bacteria were predominantly identified in the entire 17 LCS samples using culture method followed by 16S rDNA sequencing technique. TLRs 2 and 4 expression used as markers of immune response in spermatozoa and sperm dysfunction were elevated in the LCS/BS spermatozoa as compared to their fertile counterparts. A significant increase in oxidative stress indices i.e., protein carbonylation, lipid peroxidation and acridine orange test (AOT), was also observed in the LCS/BS spermatozoa. Spermatozoa lysate (both auto and heterologous), bacterial lysate (control) and synthesized MOSPD2 self-peptide were used to test their antigenicity against the autoantibodies by rocket immunoelectrophoresis (RIEP) assay. Seminal plasma from LCS/BS patients with S. agalactiae was used as the source of autoantibodies. Spermatozoa and bacteria lysate; and MOSPD2 self-peptide were able to bind autoantibodies in the seminal plasma. Besides, the self-peptide showed a dose dependent increase in the precipitation of antibody. T-cell epitope mapping of 48 Enterococcus faecalis and 91Staphylococcus aureus surface proteins confirmed MOSPD2 as a global auto-antigen. Thus, augmentation of TLR expression in LCS/BS spermatozoa inferred MOSPD2 to be a putative immunogen. Altogether, these findings will delineate the significance of MOSPD2 auto-antigen in a bacteria derived immune infertility condition.

Evaluation of Periodontal Status among Men Undergoing Infertility Treatment

Aims:

It has been estimated that >30% of male infertility cases are of idiopathic etiology. Recent studies revealed a positive connection between periodontal pockets and sperm submotility, which proposes that periodontitis may have a role in male infertility and inadequate semen quality. The aim of the present investigation was to inspect the relationship between male fertility parameters and the periodontal status of male patients attending in vitro treatment (IVF) clinic.

Materials and Methods:

The study participants comprised 85 men going to the facility for sperm investigation before semen insemination. The nature of sperm was surveyed by the WHO 2010 criteria. On the same day, male patients were examined for periodontal parameters.

Results:

The patients were determined to have either gingivitis (24.7%) or periodontitis (75.3%). Normospermia was credited to 23.5% and oligozoospermia to 43.5%. Sperm submotility was seen in 76.4% of patients. A higher number of sites with clinical attachment loss showed a positive correlation with sperm submotility and sperm count.

Conclusions:

The findings of the present study showed a conceivable relationship between male infertility, decreased semen quality, and periodontal diseases in men visiting IVF centers. Periodontitis may subsequently play a role in male infertility.

Association between a PD-1 gene polymorphism and antisperm antibody-related infertility in Iranian men

OBJECTIVE

Programmed cell death-1 (PD-1, Pdcd1), an immunoreceptor belonging to the CD28/CTLA-4 family negatively regulates antigen receptor signalling by recruiting protein tyrosine phosphatase, SHP-2 upon interacting with either of two ligands, PD-L1 or PD-L2. This study investigates PD-1 gene polymorphism in patients with antisperm antibody-related infertility

METHODS

Genotyping was performed by polymerase chain reaction and restriction enzyme digestion (PCR-RFLP), this polymorphism was genotyped in 145 Iranian subjects (61 patients with antisperm antibody-related infertility and 84 healthy controls).

RESULTS

Patients frequencies of the G/A genotype in comparison with healthy controls (38.2 % vs. 32.7 %, OR =1.21, P = 0.35) were not significantly different. However, G/G and A/A genotype frequencies between patients and healthy controls were significantly different (P = 0.042, P = 0.00001, respectively). Also, allele frequencies of this polymorphism were significantly different (P = 0.0012) in patients compared to healthy controls.

CONCLUSION

According to these results, there is a correlation between PD-1 gene polymorphism and susceptibility to antisperm antibody-related infertility in our study group.

Prostasomes are mediators of intercellular communication: from basic research to clinical implications

Prostasomes are nanosized microvesicles secreted by acinar epithelial cells of the prostate gland. Furthermore, they are intracellular microvesicles inside another larger vesicle, a so-called storage vesicle, equivalent to multivesicular bodies of late endosomal origin. Prostasomes are thought to play an important role in intercellular communication by direct interaction primarily between the immobile acinar cells of the prostate gland and the mobile spermatozoa. Prostasomes transfer not only membrane components but also genetic material to spermatozoa. They are rich in various transferable bioactive molecules (e.g., receptors and enzymes) that promote the fertilizing ability of spermatozoa. In this review, the pleiotropic biological effects of prostasomes that are relevant for successful fertilization will be discussed. The ability to synthesize and export prostasomes to the extracellular space is observed not only in normal prostate epithelial cells but also in malignant prostate cells. Release of prostasomes by prostate cancer cells suggests a role in malignant cell growth and proliferation. These findings may provide new therapeutic and diagnostic strategies.

Antisperm immunity and infertility

Immunoinfertility is one of several causes of infertility in humans. Although progress on antisperm immunity and infertility has advanced during the past three decades, the nature of a real antisperm antibody (ASA) is still poorly understood. Dozens of sperm antigens have been isolated and characterized in association with infertility. However, it is difficult to identify a single predominant target antigen that could interact with all the ASAs. There are some protective mechanisms preventing ASA production in males and females. As chronic infection, vasectomy and vasovasostomy, heavy metals, and testicular cancer and torsion may induce the production of ASAs, they may be responsible for decreased motility and sperm penetration of cervical mucus, and the blockage of the acrosome reaction and the sperm-egg interaction. Many ASA assay methods have been developed, each with advantages and disadvantages. Efforts for the treatment of ASA-mediated infertility have been attempted. However, current therapy for ASA-associated infertility is almost empiric and largely unproven.

The effect of medroxyprogesterone acetate on behavioural responses of captive female hamadryas baboons (Papio hamadryas)

Female hormonal contraception is considered here as an alternative to vasectomy for population control in social groups of captive hamadryas baboons (Papio hamadryas). While female hormonal contraceptive methods have been successful, behavioural effects of such agents represent a potential welfare concern. This study examined the effect of medroxyprogesterone acetate (MPA; 3.5mg/kg) on perineal tumescence and behaviour in three social groups (total of 3 males, 22 females) of captive hamadryas baboons. The agent had little effect on social interactions such as grooming relationships, aggression and affiliation (all P>0.05), but did cause a reduction in sexual behaviour (P<0.001). Females-mounting-females and females receiving mounting was decreased during MPA treatment compared with the minimal tumescence phase (P<0.001). Age strongly influenced the contraceptive's duration: there was a significant correlation between age and latency of return to oestrus post-MPA (r=0.832, P<0.001) with the latency increasing by 2.61 days per year of age on average. Age also influenced the frequency of behaviours such as affiliation and aggression (P<0.001 and P=0.044, respectively). The absence of adverse behavioural effects further supports the use of MPA in the hamadryas baboon, and its potential use in other non-human primates.

Antisperm antibodies and conception

Sperm have been known to be antigenic for more than a century. There is a strong body of evidence that in humans and in other species at least some antibodies that bind to sperm antigens can cause infertility. Therefore, these antibodies are of interest today for two practical reasons. Firstly, the association of the antibodies with infertility means that they must be detected and then the couples treated appropriately. Secondly, because these antibodies can induce infertility they have the potential to be developed for contraceptive purposes in humans and also for the control of feral animal populations.

Identification of Evolutionary Conserved Mouse Sperm Surface Antigens by Human Antisperm Antibodies (ASA) from Infertile Patients

PROBLEM

The presence of antisperm antibodies (ASA) in semen may impair sperm function leading to immunological infertility. The aim of the study was to identify the evolutionary conserved antigens on mouse sperm surface that react with human ASA in order to study the mechanism of autoimmune infertility.

METHODS OF STUDY

The binding of human ASA to mouse sperm was investigated by means of indirect immunofluorescence. 2D-electrophoresis was applied to separate the biotin-labelled mouse membrane proteins using isoelectric focusing followed by polyacrylamide gel electrophoresis. Cognate antigens of ASA from seminal plasma of infertile patients were analysed by Western blotting. Performing avidin-blots it was detected which of the proteins recognized were sperm surface proteins. The spots of interest were analysed by means of mass spectrometry.

RESULTS

ASA bound most frequently (36%) to the post-acrosomal region and to the midpiece of mouse spermatozoa. About 30% of ASA recognized apo lactate dehydrogenase (LDHC4) as a cognate antigen, 30% voltage-dependent anion channel (VDAC2). ASA of 20% bound to outer dense fibre protein and 20% of samples recognized glutathione S-transferase mu5.

CONCLUSIONS

Human ASA bound to specific cognate antigens of mouse spermatozoa, offering the possibility to study their functional relevance in the mouse model.

Identification of immunodominant autoantigens in rat autoimmune orchitis

Infection and inflammation of the genital tract are amongst the leading causes of male infertility. Experimental autoimmune orchitis (EAO) in the rat serves as a model for the investigation of inflammatory testicular impairment. In this study, experiments were conducted to identify the molecules that are responsible for eliciting the autoimmune attack on the testis. EAO was induced in in-bred Wistar rats by active immunization with testis homogenates (EAO group I). Development of disease was observed using histological techniques and a new non-invasive three-dimensional (3D) imaging technology for in vivo monitoring, termed flat-panel volumetric computed tomography (fpvCT). Examination of control and EAO testes demonstrated the superior image quality of high-resolution fpvCT. A proteomics approach using 2D SDS-PAGE and immunoblotting analysis with EAO sera identified 12 spots. Seven were subsequently identified by mass spectrometry as heat shock proteins 60 (Hsp60) and 70 (Hsp70), disulphide isomerase ER-60, alpha-1-anti-trypsin, heterogeneous nuclear ribonucleoprotein H1 (hnRNP H1), sperm outer dense fibre major protein 2 (ODF-2), and phosphoglycerate kinase 1. Hsp70, ODF-2, hnRNP H1, and ER-60 were identified by all EAO sera studied. To test the capacity of the identified proteins to elicit testicular autoimmune disease, recombinant proteins were used either individually or in combination to immunize rats (EAO group II). In all groups, the incidence of EAO was 25%. Inflammatory-type (ED1+) and resident (ED2+) macrophages, lymphocytes (CD45RA+), and dendritic cells (Ox-62+) were strongly increased in EAO group II animals, comparable to the testes of EAO I rats. Pre-immunization with a low dose of recombinant Hsp 70, hnRNP H1 or ODF-2 before induction of EAO with testis homogenate significantly delayed the onset of EAO but could not prevent disease. The identification of testicular autoantigens will allow a better understanding of disease pathogenesis and could provide a basis for the development of novel therapies for inflammation-based male infertility.